This invention relates generally to field of lighter-than-air craft and more specifically to a system for stabilizing the weight of such airships by making water ballast from the exhaust gases created by burning hydrocarbon fuel for propulsion or other purposes.
In such airships, the buoyancy is usually controlled by ballast which is added and/or dumped to compensate for lift variables such as helium volume (changes due to leakage and atmospheric heating) and, more importantly, the weight of fuel consumed. In the case of long range maritime airships, this ballast is customarily sea water which necessitates frequent descents to the surface to take on additional ballast. Not only is this operation hazardous in high wind, high seas conditions, but, especially in the case of maritime surveillance airships, this operation reduces the effectiveness of the surveillance during those periods when the airship is at the surface taking on ballast. Moreover, considerable time and skill is needed on the part of the crew to continuously calculate the state of buoyancy and manage the ballast accordingly.
It has already been suggested to simply condense water from engine exhaust gases and store this water as ballast. See, for example, U.S. Pat. Nos. 1,426,047; 1,576,859; 1,598,002; 1,645,065; 1,653,603; 2,310,767 and 2,479,766. However, the excess weight or bulk, parasitic power loss, and lack of dependability of previous designs has limited their value to various minor degrees of success for over fifty years.
Some of the more serious problems of these prior systems are discussed in the aforementioned U.S. Pat. Nos. 1,653,603 and 2,078,532.
Therefore, it is an object of the present invention to overcome the Problems and disadvantages of previous systems and provide an improved means for automatically controlling the buoyancy of a lighter-than-air craft.